This invention relates to novel anaerobic curing compositions containing conventional polymerizable (meth)acrylate monomers, free radical initiators, and polymerizable activators therefor. It further relates to the use of the improved anaerobic compositions as adhesives and sealants.
Anaerobic compositions are well-known in the art. They are so formulated or treated that the compositions remain in an uncured state over long periods of time provided that the compositions are exposed to an adequate supply of air or oxygen throughout that period, but which polymerize spontaneously upon the exclusion of air or oxygen therefrom, as when placed between non-porous surfaces (e.g. metal or glass). Depending upon the exact formulation, such compositions may be used as adhesives or sealants.
These anaerobic formulations generally contain a peroxy initiator and/or benzosulfonimide (saccharin) as activator therefor. Typical of such formulations are those disclosed in U.S. Pat. Nos. 2,895,950; 3,775,385; 3,957,561; 4,054,480 and 4,038,475. The types of activator systems represented by the teachings of the prior art patents represent separate components which are merely blended into the acrylate or methacrylate based anaerobic formulation so as to provide the free radical source needed for polymerization.
It is an object of the present invention to provide a monomeric activator which can be copolymerized directly into the backbone of the acrylate or methacrylate anaerobic monomer. By incorporating such a polymerizable monomer into the anaerobic system, final adhesive compositions characterized by superior strength properties can be achieved.